I think that going with a 6.5 caliber, like the Grendel would be a step up; only barrel swaps would be necessary to convert the arsenal. But in defense of the 5.56, my Son did six years in the service, one year in Iraq, and from his experience, he would take the M4 any day over an M14, or an AK. He says, it does what it is designed to do. He says if you want to shoot someone a thousand yards away, go with a weapon that can do that. If you need to shoot through four foot thick walls, go with a weapon that will do that. If you have to fight mud hut to mud hut, streets, never more than 400 yrds, light, handy, easy to train soldiers with, go with a weapon that will do that, the M-4. If you look at years served by the various calibers, the .30-06, roughly fifty years, from '03 to '53. The 7.62, ten years, from '53 to '63, and the 5.56 from '63 to now, forty-nine years, it must not be too bad. People have disparaged it as a piece of shit round since it was adopted, yet it stays in service. It had it's problems, without question in the early years, but I think that the current round and platform, are rather remarkable. And the people that say it cannot kill a 140 lb. raghead, routinely kill 180 lb. deer with it, by the hundreds of thousands a year. I used to have a slow twist 5.56, and shot several deer with the plain Jane military 55 gr. FMJ, and the exit wounds looked like I had shot them with my 6mm Remington with 100 gr. SP's. I attribute that to the bullet "yaw and tumble" that the slow twist may have caused. That debate has gone on since '63. Almost all of the "professional" pig hunters around here, M-4's, or older variants. 400 lb. hogs, legs up. During the 1800's, MILLIONS of soldiers were killed with calibers that we wouldn't trust to kill a coyote with hardly. The Spencer, the .44 Henry, etc.; all rather anemic compared to the 5.56, yet they killed men too. How many humans have been killed with the .45 Colt, the .45 ACP, the .38 Special, and the 9mm. Yes, all at close range, but that was what THEY were designed to do. MM